When i apply breaks the steering tends to swerve towards the left hand side. Not sure what might be causing this, i would appreciate any help/comment/thoughts. Thank you.

Your stability control system has a failure, have the system scanned to pull the fault codes.

most car swing to what ever the camber is on the road if it just drifts across slowley this is normal if it sudenly goes very sharpley check these things front breaks are not binding on wheel bearing track rod end broken or week springs worn shocks steering rack faulty or stiff check these things out first hope this helps ivan uk

If you swerve the car back and forth and the sound dissapeers when swerving to the left( reducing the weight on front left tire) this could indicate a wheel bearing problem

Do you mean the car pulls to one side as you drive, severely?
If this came on suddenly, there is a good chance something has gone wrong. If it has gotten worse slowly It may just need an alignment. I would take it to get the alignment checked. That will reveal any serious problems too.

`right one of two problems ,firstly remove the rear drums and check for a fluid leak as a slight smear of fluid will cause the exact problems you describe ,if the rear shoes are dry then push the cylinder each side to make sure its not seized ,secondly check the load sensing valve which will be under the chassis above the back axle,if that appears ok and not seized then remove the master cylinder and take the piston out and check the rubbers and the cylinder bore for wear ,but mainly this fault is caused by the brake shoes having a slight amount of brake fluid contamination and it causes the brakes to grab

Check ball joints and tie rod ends for play. Jack the truck up on the frame and try to move the wheel up and down for ball joints and side ti side for tie rod ends. Also make sure you check the idler arm on passenger side and pitman arm on steering box. None of the parts should any play whatsoever. If there is any play in them when you try to move them then replace them.
There could also be excessive play in the steering box but that shouldn't make it swerve back and forth. That would just let it wander to one side or the other until you corrected it by turning the wheel. Hope this helps.

I would say that the left hand brake caliper is not releasing and either needs replacing or have a repair kit fitted.

Or the constant velocity joint on the left is seizing up due to either road dirt ingress or a cracked bearing

Brakes
When you apply the brakes the piston inside the caliper is supposed to move out to apply pressure to the brake pads.
When you remove the braking effort it is supposed to relax allowing the pad to release
Yours is not doing that so it will cause the car to pull to one side.

Is your car the turbo charged or non tubo car. On the turbo car the power steering pump is on the front right hand side. all you need to do is put the belt back on and apply pressure til the belt is tight then tighten up the bolts that hold the power steering pump.

If this only happens when you are applying the brakes it could be a stuck brake caliper or something else to do with the braking system.  To narrow it down go for a drive with frequent repeated stops to get the brakes warm. Check the amount of heat coming from each of the wheels and compare them side to side.  If a brake caliper is seized, the wheel on the opposite side of the pull should be much hotter than the wheel on the side of the pull.  (If it pulls to the left and the the right brake is much hotter than the left, the right brake caliper is stuck.  I usually use an infra red thermometer and check the temps of each brake rotor to determine the problem. If you find that is the problem, change the brake pads, rotors and make sure to clean and lubricate all the moving parts on the caliper.

Hi, You need to be checking the track rod end, the bottom ball joint and bush, the wheel bearing, and the shock absorber, all on the left hand side. You could take it to have the tracking checked and they may notice something whilst checking it if you mention it to them. Cheers.